Some Thoughts on the Double Forearm Block

Double Forearm Block in a Walking Stance.

The ITF Encyclopaedia calls the double forearm block (doo palmok makgi / 두 팔목 막기) “one of the strongest forms of blocking” (Vol. 3, p. 224).

(You can read a description of how to perform a double forearm block at eHow.)

One might think that it is because the blocking arm is supported by the other arm, but this is merely an optical illusion as it is only the “second knuckle of the little finger” that presses against the “elbow at the moment of the block” (Vol. 3, p. 224), as seen in the photo on the side. The support provided by the knuckle of the little finger is negligible. The reason the other arm is brought up is rather as a guarding, ready or resting position from where one can “quickly shift [that] forearm into another block while still blocking with the [first]” (Vol. 3, p. 224). The photos below show how the hand that was brought forward is brought into play to block a second attack.

Visually, the only differences between the double forearm block and the inner forearm outward block (an palmok bakooro makgi) is that the former has the other arm brought forward just in case it is required for a secondary block, while the latter has the 'reaction arm' pulled back to its customary place at the side of the hip. Bringing the other arm forward with the double forearm block does not contribute substantially any more than pulling the 'reaction arm' back when performing the inner forearm outward block.

A typical outward block with the fist of
the 'reaction arm' pulled back to the hip.

What makes the double forearm block “one of the strongest forms of blocking” has less to do with bringing the other hand forward and more to do with the angle at which the block intercepts the opponent's attack.

An inner forearm outward block (as in the above photo) intercepts the attack much more perpendicularly.

Approximate angles of interception against an incoming attack.
The red arrow on the left intercepts the attack perpendicularly.

(Note: The illustrations show generalised estimations, not exact angles.)

The illustration (viewed from above) shows on the left the vector of an attack (black) moving towards the defender. The first red arrow (left) shows how a perpendicular defence would intercept such an attack. There are very few blocks in Taekwon-Do that intercept attacks in this way. Instead, blocks usually intercept the attack at an angle as depicted by the red arrow on the right.  The inner forearm outward block is a typical example of a block that intercept an attack like this. While the angle of a typical outward block is not completely perpendicular, the weight of the force is more perpendicular, i.e. towards the left in the example, than forward. This is not the case with the double forearm block.

Approximate angles of interception of an outward block (left)
and double forearm block (right) against an incoming attack.

The above illustration shows the angle of interception of an outward block on the left, compared to the angle of interception of a double forearm block on the right. What you will notice is that the outward block's interception leans more towards a perpendicular interception, while the double forearm block's interception is much more head-on. The next illustration shows the angle of interception of a double forearm block (below left) and the vectors of an actual head-on collision (below centre).

Approximate angles of interception of an incoming attack.
The central figure depicts a 'head-on' collision of the attacker's
attacking tool and the defender's blocking tool.

Such a head-on collision of forces may be imagined as the defender punching the attacker's fist, like we might see in a Jet Li movie where he punches his opponent's punches, so that the angle of vectors correspond, but the direction of the vectors are exactly opposite. What we have then is a good example of Newton's Law of Motion regarding Reaction Force, where two forces moving in opposite directions hit each other resulting in a combined force equal to the sum of the original two forces.

Such a head-on collision of one's blocking tool with the attacker's attacking tool is never advised because the culmination of forces could cause serious injury to yourself. Furthermore, trying to stop the incoming attack from the front is much more difficult because the attack's surface area tends to be smaller from the front (the front of a fist is a smaller area to block than the side of an arm) and it is more difficult to judge the distance of something coming straight at you. For these reasons blocks generally intercept attacks at an angle from the side, rather than straight from the front. The angle helps to deflect the attack's forward force, changing it's direction away from your vital spots. What is interesting to note, however, is that the less perpendicular the block is, in other words the more “head-on” it is, the harder it is; the reason being the culmination of the two opposing forces. On the other hand, if the block is too “head-on”, it might easily miss the target or slip pass the target as depicted on the right in the illustration above.

A forearm guarding block in an L-stance.

What makes the double forearm block “one of the strongest forms of blocking” is its ability to intercept the attack while maintaining a loaded amount of forward force; there is definitely more forward force than perpendicular force, contrary to a normal outward block where the perpendicular force outweighs the forward force.

In this regard, the double forearm block functions in quite the same fashion as the basic forearm guarding block, which – if not used merely as a guard, but actually to block an attack – intercepts a straight incoming attack at pretty much the same angle as a double forearm block would. An obvious difference is that the double forearm block can only be done with the inner forearm as the blocking tool. Although the guarding block is usually performed with the outer forearm as the blocking tool, other blocking tools, like the inner forearem, knife-hand and reverse knife-hand, can also be employed.

Side view of a double forearm block
in walking stance.

Although I have adamantly argued at the beginning of this post, based on the ITF Encyclopaedia, that the purpose of the non-blocking hand in a double forearm block is not to support the blocking arm, but merely to bring the hand up in case it is needed as a secondary block, I foresee that it can actually have an augmenting support function. If you are to use the double forearm block and the attack were to push against your forearm, it is feasible that your blocking arm might tilt in such a way that it pushes against your "supporting" fist. While the non-blocking arm does not actually contribute to the force of the block, it could under certain circumstances have an augmenting support function. It is for this reason that the double forearm block is sometimes referred to as the augmented block.

An interesting observation about the double forearm block is that in the patterns it is never (as far as I know) performed at middle section. In the patterns it is generally performed at high section in a walking stance, and occasionally at low section, but then only as a pushing block, usually in an L-stance. The ITF Encyclopaedia shows some examples of the double forearm block being used at middle section, so clearly it can be used at that height. That the patterns should only employ it at high section may suggest a strategic use for the double forearm block, which, unfortunately, is not explained in the encyclopaedia, but is worth exploring.
 
Students are usually introduced to the double forearm block for the first time at 5th geup when the learn the pattern Yul-Gok. 


Photo Credits:
Colour photos are from Sonkal.
Black-and-white photos are from Volume 3 of the ITF Encyclopaedia.